Wiredrawing die



H. BLOUNT.

Dec. 19, 1922.

HARRY BLOUNT, OF OAK PARK, ILLINOIS, ASSIGNR' TO WESTERN ELECTRIC COMPANY, INCORPORATED, or New YORK,

N. Y., A CGRPORATION F .NEW YORK.

winnnnawmo mn.

application flied nay 12, i920. Semi Na'aeasas.

of Illinois, have invented certain new and useful Improvements inVViredrawing Dies, .of which the following is a full, clear, conoise,and exact description.

This invention relates to wire drawing dies, and has for its object toproduce a form of die for wire drawing operations which will permit thedrawing of wire therethrough at high speed without breakage of the wireand which will be efficient and accurate and will have a long life.

Investigation of former wire drawing machines has disclosed that theyare necessarily limited in their speed of operation due to lack of diescapable of permitting 2c-the drawing of wire therethroughI at highspeeds. These machines are now operating at speeds as high as wire canbe commercially drawn through the dies used therein. After a long seriesof tests with dies ot' the types heretofore used and also with Variousdiierent designs of dies made up during the course of my investigation,I have discovered that the relation between the length and the diameterof the wirel reducing opening and also the contour thereof at theentrance end materially influence the pull requiredto draw the wirethrough the die, the accuracy of the lsize of the drawn wire, the speedat which wire l may be' drawn' through the die without breakage, and thelength of time which the die can be used for a given size of wire. Forexample, there is a definite relation between the length of the 'wirereducing porio tion of the die and its diameter which 'will provide thegreatest'resistance to wear on the die and at the same time will.provide for the minimum resistance to the pull of the wire through thedie, while insuring that the wire will undergo a complete physicalchange from the larger to the desired reduced size. Also, it has beenfound that if the wire reducing opening is connected with the mouth` ofthe die by means of a curved portion which bears a certain relation tothe diameter of the wire reducing opening, the amount of pull requiredto draw the wire through the die will be reduced to a minimum, therebyeliminating 56 the tendency of the wire to break and reducing the amountof friction between the die and the wire.

The dimensions which have been determined as best adapted for thestricture of the die are those in which the length of the reducingportion is approximately equal to its'diameter, while the contourthereof at the entrance to the wire reducing portion is rounded on aradius approximately i equal to twice the diameter of the smallestlportion of the wire reducing opening. Dies having this construction arecapable of drawing number 19 to 40 vinclusive B. & S. wire gauge copperwire commercially at approximately 2500 feet per minute without breakageof the wire, whereas with former dies for drawing these sizes ot wirethe machines have been operated at a maximum speed of reduction of 1600feet per minute.

Dies made either from chilled iron or from diamonds having the.proportions abovedescribed are capable of highispeed reductions for alength ot' time that is commercially satisfactory.

i In thel drawings illustrating this invention 1- Fig. 1 is a verticalsectional view of a die illustrating this invention;

Fig. 2 is thesame as Fig. 1 with the wire i .by the wire as it is drawnthrough the die,

and

Fig. 4 is a fragmentary plan View of the die.

As shown in the drawings, 5 designates a die body which may be supportedby a suitable supporting member 6 fragmentarily shown. At one end ofthis die there is provided a mouth or tapered opening 7 which 'is largerat its upper end than the diameter of a wire` 8 to be reduced and istapered inwardly toward a straight sided reducing portion 9 ,which ,hasthe diameter of the drawn wire 10. The length L of the narrowed orreducing portion of the opening 9 should be approximately equal to thediameter or oZ of this'opening in order that the wire -will undergo.such ph sical changes that it will become complete y set in its reducedsize before emerging from the die and the die will not be subjected totoo great wear. AlsoV is length is not so great as to Aintroduce@extrafriction to the drawing ofthe wire.

Connecting -the' mouth or tapered p0r' to twice the diameter d of thestraight sided reducing portion 9. This curvaturev has been found tooffer the least resistance to the drawing of the wire. lAt its lower endthe straight' sided or reducing portion 9 is slightly beveled orrounded, as sho-wn at 13, to prevent cutting or abrading of the wire incase it becomes necessary to backup the wire in the die for any reason.

What is claimed is: l

1. A wire drawing die having a reducing portion in which there is astraight portion having as diameter.

2. A wire drawing die having a straight reducing portion the entranceinto which when viewedl in crosssection is rounded on a radiusapproximately equal to twice the diameter of the straightreducingportion.

3. A wire .drawing die having a wire reducing opening in which there isa straight portion having approximately the same length as diameter andin which the approximately the same length ventrance end, when viewed incross section,

is rounded on a radius approximately equal to twice the diameter of thestraight portion.

In witness whereof, I hereunto subscribe my name this 28th day of AprilA.. D., 1920.

HARRr BLOUNT.

